Many countries think of TB as a disease of the past and this lack of awareness results in shortfalls in funding and a lack of political will to aggressively combat the disease.
But a new WHO report on tuberculosis published this week makes it very clear that TB is a disease of the present. An estimated 10.4 million people were infected in 2015, an increase over previous years. Some 1.8 million died from the disease, or more than 34,000 people a week on average; far more than Ebola ever claimed. And almost 600,000 people are estimated to have multi-drug resistant (MDR) TB.
It's likely to be a disease of the future as well, especially in countries with the poorest populations. But it does have one significant point in common with Ebola — both diseases thrive where the medical infrastructure is weakest. "We face an uphill battle to reach the global targets for [controlling] tuberculosis," said WHO director general Dr. Margaret Chan.
We spoke to experts to understand some of the challenges of controlling TB. Here are some key reasons for the grim report.
It's difficult to accurately count TB cases.
Some countries with a high incidence of TB have realized that their previous numbers woefully understated the true number of cases. In India, for example, WHO estimates that almost half of the estimated 2.8 million cases are never reported to health authorities. A battery of different approaches taken in India since 2000 have made clear how many cases were going unreported. Health authorities undertook several surveys — including one large-scale survey in the state of Gujarat. They also studied sales of TB treatment drugs and started enforcing rules for doctors to report TB cases to national health authorities. India's revised estimates drive up global estimates. Other countries have also had to revise estimates because of past undercounting.
And there are countries where either the latest surveys are decades old or there's no data at all. In areas like Central Africa few countries have the resources to carry out exhaustive surveys. This could mean there are hidden pockets of undetected cases.
TB is inextricably linked to poverty.
TB spreads more easily in crowded conditions, and malnutrition makes people more likely to activate, or switch from latent to active, contagious infections.
The disease also drags its victims down financially. "Their lives are absolutely devastated," says Dr. Jennifer Furin of Case Western University, who provides care for TB patients in developing countries like South Africa. Over the long course of illness, families drain their savings trying to obtain treatment for infected members. One of WHO's goals is to reduce the catastrophic cost of TB treatment. Several developing countries are assisting TB patients with food supplements and direct cash payments. WHO is working with various countries to assess how many TB cases suffer catastrophic health care costs.
The disease also weakens its victims to the point that they can't work, so families lose needed income. TB, and especially drug-resistant TB, carry a stigma. The wider community or extended family often ostracizes TB patients, depriving them of what meager resources they might have otherwise. Finally, sick family members spread it to others in their households, perpetuating the cycle.
Newer treatments against TB aren't in wide use.
In 2012, the FDA approved Bedaquiline, the first new drug to treat TB in 40 years. Another drug, Delamanid, has been approved in the European Union. Both drugs were developed to treat multi-drug resistant TB. Clinical trials have shown that the drugs clear TB from sputum effectively. Although Bedaquiline has been used in 70 countries, only six — France, South Africa, Georgia, Armenia, Belarusk, and Swaziland use it routinely.
Why not more? Health authorities have to play a delicate balancing game with TB drugs, though. Indiscriminate use can lead to drug resistance. So new drugs are sometimes held back to prevent rapid resistance to them. But this approach is "protecting the drug instead of the patients," Furin says.
Health authorities also tend to take a cautious approach to new drug deployment because of fears of unexpected side effects. But Furin notes that patients with drug resistant TB have a 5-year survival rate of less than 20 percent. Concerns about drug toxicity should be secondary to ensuring their survival, she said.
Efforts to control TB focus on symptomatic cases rather than early stage or pre-symptomatic cases.
Investing in TB control efforts up front can reduce ongoing costs to treat patients later on, argues Dr. Salmaan Keshavjee of Harvard Medical School.
"We need to recalibrate," he says. "Right now, TB control is set up so that you only show up when you're dying." Most developing countries, including many countries with the highest TB burden, only treat symptomatic cases instead of treating people who've been in contact with active cases, says Keshavjee. Focusing on symptomatic cases makes it possible for people with TB to spread the disease to those closest to them.
Keshavjee acknowledges that it's expensive to hunt for active cases and to treat potential cases with preventive medications. But he points to efforts in countries like Russia, where initial large investments have paid off in lower TB case counts in subsequent years.
It's critical, Keshavjee adds, to build a health system that offers care for multiple diseases instead of treating them individually, which is more wasteful. Keshavjee believes that infrastructure built up for TB control can become an asset to promote the overall health of a country's population and fight other diseases, like hepatitis, that plague developing countries.